CRESTED BLACK MACAQUE
Geographic Distribution and Habitat
Crested black macaques (Macaca nigra), also known as Celebes crested macaques, are endemic to Indonesia. They are restricted to just a handful of islands in the archipelago: Sulawesi, Manadotua, and Talise. Historically, crested black macaques were also found on Lembeh Island, but they have since been extirpated—or made locally extinct—from that island. There is an introduced population on the island of Bacan, but scientists believe that the genetic viability of this population might be too low to be of conservation value. Crested black macaques live in the lush rainforests for which Indonesia is well known. Unfortunately, however, these rainforests are disappearing. Crested black macaques are therefore forced to eke out an existence in disturbed and logged forests, as well as grassland and even farm fields if they are surrounded by forest.
Size, Weight, and Lifespan
Female crested black macaques measure 18–22 inches (45–57 cm) in length and weigh about 12 pounds (5.5 kg) on average. Males are between 20–22 inches (52–57 cm) in length and weigh an average of 22 pounds (9.9 kg). Crested black macaques live an average of about 18 years, although they have been known to live up to 34 years in captivity.
Crested black macaques are large-bodied monkeys, with long arms and legs and a very short (¾ of an inch or 2 cm) nub of a tail. They are sometimes misidentified as apes because their tails are so difficult to see. As their name implies, they are black all over, with the only exception being the bright pink pads on their rears called ischial callosities. Their faces are very long—almost horse-like—more similar in shape to a baboon’s than to most other macaques’. Their large, round eyes are featured prominently on their face and are very close together, which gives them binocular vision. The “crested” part of their name comes from the tuft of black hair sprouting up from the tops of their heads, resembling a fauxhawk hairstyle. Juveniles are paler than their parents, sometimes more brown than black, and they are not born with a crest. As males age, their hair grays and becomes coarser. There are differences between the sexes, with females being paler in color than males. The most obvious difference between the sexes, however, is size. Males are significantly larger than females.
Crested black macaques are primarily frugivorous—that is, they mostly eat fruits. Figs are a very important component of their diet. However, they supplement their diet with leaves, insects, small animals, and even agricultural crops like coconut, corn, and sugar palm.
Behavior and Lifestyle
Crested black macaques are primarily, though not exclusively, terrestrial. This means they spend the majority of their time, about 60%, on the ground. Like other macaques, they are diurnal—i.e., awake during the day. Typically, they spend their mornings socializing. As with most primates, they are extremely social and rely heavily on their groups. In the afternoon, they forage. They travel about 1.5 miles (2.4 km) per day, although in undisturbed forests they travel shorter distances because of the higher abundance of fruit. At night, crested black macaques find a tree to spend the night in. This helps to keep them safe from terrestrial predators.
Sometimes crested black macaques store extra food in their cheek pouches for later, similar to a hamster.
A crested black macaque gained international attention in 2011 when she took her “selfie” with wildlife photographer David Slater’s camera. It started a years-long copyright battle to determine whether an animal can own a copyright. In the end, courts decided that animals cannot own their own copyright, and that works “created by a non-human” can’t be copyrighted at all. Thus, the images are in the public domain. Despite the legal headaches, most can agree that the photo and the case surrounding it brought positive attention to a critically endangered species that few were previously familiar with.
(Out of respect for the human photographer, for whom these legal battles caused considerable duress, we won’t share the photo here. You can look it up easily enough if you wish.)
Crested black macaques live in large multi-male multi-female groups that can contain up to 100 individuals, though groups as small as five have also been observed. These groups are larger than those of most other macaques. The typical sex ratio between males and females is about five females for every three males. Relations between females are usually peaceful, and they do not have a dominance hierarchy. Conflicts among females are rarely aggressive and are usually resolved easily. By contrast, relations between males are much more volatile, with males displaying frequent aggression with each other. Males have a linear dominance hierarchy, which they establish and maintain through their interactions with one another. Groups’ home ranges vary in size from 160–870 acres (64–350 ha) and are larger during the rainy season. These home ranges overlap with those of other crested black macaque groups.
Body language is a very important form of communication among crested black macaques. For example, it is used between males to determine their hierarchy. Lower-ranked males indicate their submission through behaviors like grimaces and lip smacking, while higher-ranked males display aggression through staring, grinning, lunging, and chasing. Even a yawn doesn’t necessarily mean that a macaque is sleepy: when performed by a male, it shows off their very impressive canine teeth and can be a sign of aggression. Research has shown that, like humans, crested black macaques respond to even very subtle differences in facial expressions.
Vocalizations are also very important. Crested black macaques are known for their bird-like call that is used when intervening in conflicts. Higher-ranked males vocalize complex calls more often than lower-ranked males. It is believed that some crested black macaque vocalizations are linked to reproduction. Female vocalization during copulation may actually hint at the likelihood that she is ovulating, although this is not fully understood by scientists. Crested black macaques also use olfactory communication—messages through smell. For example, females emit a chemical signal when they are ovulating that attracts males.
Crested black macaques are polygynandrous, which means that both males and females have multiple mates. Mating occurs year-round, but there is a period of high fertility among females from June to August, and births most often occur between January and May. Female crested black macaques signal their readiness to mate through genital swellings and olfactory cues. This swelling also sometimes happens when females are not fertile, leading to non-procreative copulation. One evolutionary explanation for this is that it may confuse paternity, leading to multiple males protecting the mother and her offspring, since they might be the father of her baby.
Females approach dominant males for mating more often than they approach lower-ranked males. Receptive females are also closely guarded by dominant males. Despite these challenges, lower-ranked males still fight for their shot to mate, and they actually mate with about the same frequency as more dominant males. A female is pregnant for about six months, after which she births one baby. Females, on average, have a baby about every two years. Males and females mature at different rates, even though the hormonal processes that control maturation are the same in both. Babies are primarily cared for by their mothers. In their early stages, they cling onto her belly for protection. Sometimes, juvenile females also help to care for the young, supervised by the babies’ mothers.
Crested black macaques are not known to have any significant predators besides humans, but they serve as predators themselves to the insects and small animals that they eat. As frugivores, they are important seed dispersers as well, particularly for fig trees. Many macaques have what’s known as a “commensal” relationship with some insect-eating birds. A commensal relationship is one in which one species is unaffected while the other benefits. In the case of some macaques, their foraging activities stir up insects in the canopy, which birds then swoop in to eat.
The International Union for Conservation of Nature lists the crested black macaque as Critically Endangered (IUCN, 2020), appearing on the IUCN’s Red List of Threatened Species. This is the last step before extinction in the wild. Since systematic population surveys began in the 1970s, severe population loss has been documented. It is believed that the population of crested black macaques has decreased by more than 80% in just the past 30 or so years, about three generations. Scientists believe that there is just a single viable population of crested black macaques left, in the Greater Tangkok Conservation Area. However, this population lives in a degraded and fragmented habitat. Outside of this population, crested black macaques mostly exist in very small, scattered groups. These groups are so small that they likely won’t survive long-term.
The main threats against crested black macaques are hunting pressure and habitat loss. Crested black macaques are frequently hunted for meat throughout their range, and their meat is an important cultural food for special occasions and large gatherings among the local people. Unfortunately, this hunting puts immense pressure on a highly threatened species. Beyond subsistence hunting, the macaques are also trapped as crop pests, since they are known to eat from gardens and agricultural fields. Some crested black macaques are also caught for the pet trade.
Indonesia is one of the most biodiverse countries in the world. It contains the third largest area of rainforest in the world, which is spread out over 18,000—yes, thousand—islands. Unfortunately, much of Indonesia’s historic habitat has been lost to deforestation. While the country is making strides in curbing its rate of deforestation, its rate of reforestation—that is, the replanting of trees that have been lost—is still very low. Reforestation will not only be necessary to provide habitat for the species that depend on it but also as an important part of the global response to climate change.
Climate change is another looming threat to crested black macaques and a particularly poignant one for these island-dwelling animals. Species that are already endangered, occupy a relatively small range, and face significant temperature increases are the most at risk—and crested black macaques tick all of those boxes. Research shows that climate change has already pushed 8% of primate species past their ideal temperature range. Crested black macaques are already experiencing temperatures that are hotter than their historic thresholds, and this will only increase as the climate crisis worsens. And because they are limited to just a small handful of islands, they can’t simply migrate to find more optimal habitats as the climate warms. This increased heat—let alone the myriad of other changes associated with climate change, like altered precipitation patterns and shifting fruiting schedules—will only add stress to a species that is already critically endangered.
Crested black macaques are listed in Appendix II of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival. Crested black macaques occur in a number of protected areas. However, scientists believe that the only viable population lives in the Greater Tangkok Conservation Area on the island of Sulawesi.
Conservation scientists point to a dual-sided approach as the best chance of reducing the threat of hunting pressure to crested black macaques. On the supply side, there must be much stronger enforcement of hunting laws. On the demand side, education programs should be developed to promote the conservation value of crested black macaques, the health risks associated with eating them, and to promote alternative livelihoods through ecotourism and agriculture that is in harmony with the surrounding environment. Further research is another important component of the crested black macaque conservation strategy. Large-scale monitoring surveys, such as those that utilize camera traps, are important for understanding the monkeys’ range and population trends.
- Clark, P. R., B. M. Waller, A. M. Burrows, et al. 2020. Morphological variants of silent bared-teeth displays have different social interaction outcomes in crested macaques (Macaca nigra). Am J Phys Anthropol, 173: 411– 422. https://doi.org/10.1002/ajpa.24129
- Higham, J.P. 2023. The Sexual Selection Landscape and Sexually-Selected Traits of the Crested Macaque (Macaca nigra). Int J Primatol. https://doi.org/10.1007/s10764-023-00354-x
- Johnson, C., H. Hilser, M. Linkie, et al. 2020. Using occupancy-based camera-trap surveys to assess the Critically Endangered primate Macaca nigra across its range in North Sulawesi, Indonesia. Oryx, 54(6): 784-793. doi:10.1017/S0030605319000851
K. Clare Quinlan, May 2023